<template>
  <el-color-picker
    size="small"
    class="theme-picker"
    popper-class="theme-picker-dropdown"
    v-model="themeVal"
  ></el-color-picker>
</template>

<script>
import { mapGetters } from "vuex";
const version = require("element-ui/package.json").version; // element-ui version from node_modules
const ORIGINAL_THEME = "#409EFF"; // default color
export default {
  name: "topColor",

  data() {
    return {
      themeVal: ORIGINAL_THEME
    };
  },
  created() {
    this.themeVal = this.theme;
  },
  watch: {
    themeVal(val, oldVal) {
      this.$store.commit("SET_THEME", val);
      this.updateTheme(val, oldVal);
    }
  },
  computed: {
    // ...mapGetters(["theme"])
  },
  methods: {
    updateTheme(val, oldVal) {
      if (typeof val !== "string") return;
      const head = document.getElementsByTagName("head")[0];
      const themeCluster = this.getThemeCluster(val.replace("#", ""));
      const originalCluster = this.getThemeCluster(oldVal.replace("#", ""));
      const getHandler = (variable, id) => {
        return () => {
          const originalCluster = this.getThemeCluster(
            ORIGINAL_THEME.replace("#", "")
          );
          const newStyle = this.updateStyle(
            this[variable],
            originalCluster,
            themeCluster
          );

          let styleTag = document.getElementById(id);
          if (!styleTag) {
            styleTag = document.createElement("style");
            styleTag.setAttribute("id", id);
            head.appendChild(styleTag);
          }
          styleTag.innerText = newStyle;
        };
      };

      const chalkHandler = getHandler("chalk", "chalk-style");

      if (!this.chalk) {
        const url = `https://unpkg.com/element-ui@${version}/lib/theme-chalk/index.css`;
        this.getCSSString(url, chalkHandler, "chalk");
      } else {
        chalkHandler();
      }

      const link = [].slice.call(
        document.getElementsByTagName("head")[0].getElementsByTagName("link")
      );
      for (let i = link.length - 3; i < link.length; i++) {
        const style = link[i];
        if (style.href.indexOf("app") != -1) {
          this.getCSSString(style.href, innerText => {
            const originalCluster = this.getThemeCluster(
              ORIGINAL_THEME.replace("#", "")
            );
            const newStyle = this.updateStyle(
              innerText,
              originalCluster,
              themeCluster
            );
            let styleTag = document.getElementById(i);
            if (!styleTag) {
              styleTag = document.createElement("style");
              styleTag.id = i;
              styleTag.innerText = newStyle;
              head.appendChild(styleTag);
            }
          });
        }
      }

      const styles = [].slice
        .call(document.querySelectorAll("style"))
        .filter(style => {
          const text = style.innerText;
          return (
            new RegExp(oldVal, "i").test(text) && !/Chalk Variables/.test(text)
          );
        });
      styles.forEach(style => {
        const { innerText } = style;
        if (typeof innerText !== "string") return;
        style.innerText = this.updateStyle(
          innerText,
          originalCluster,
          themeCluster
        );
      });
    },
    updateStyle(style, oldCluster, newCluster) {
      let newStyle = style;
      oldCluster.forEach((color, index) => {
        newStyle = newStyle.replace(new RegExp(color, "ig"), newCluster[index]);
      });
      return newStyle;
    },

    getCSSString(url, callback, variable) {
      const xhr = new XMLHttpRequest();
      xhr.onreadystatechange = () => {
        if (xhr.readyState === 4 && xhr.status === 200) {
          if (variable) {
            this[variable] = xhr.responseText.replace(/@font-face{[^}]+}/, "");
          }
          callback(xhr.responseText);
        }
      };
      xhr.open("GET", url);
      xhr.send();
    },

    getThemeCluster(theme) {
      const tintColor = (color, tint) => {
        let red = parseInt(color.slice(0, 2), 16);
        let green = parseInt(color.slice(2, 4), 16);
        let blue = parseInt(color.slice(4, 6), 16);

        if (tint === 0) {
          // when primary color is in its rgb space
          return [red, green, blue].join(",");
        } else {
          red += Math.round(tint * (255 - red));
          green += Math.round(tint * (255 - green));
          blue += Math.round(tint * (255 - blue));

          red = red.toString(16);
          green = green.toString(16);
          blue = blue.toString(16);

          return `#${red}${green}${blue}`;
        }
      };

      const shadeColor = (color, shade) => {
        let red = parseInt(color.slice(0, 2), 16);
        let green = parseInt(color.slice(2, 4), 16);
        let blue = parseInt(color.slice(4, 6), 16);

        red = Math.round((1 - shade) * red);
        green = Math.round((1 - shade) * green);
        blue = Math.round((1 - shade) * blue);

        red = red.toString(16);
        green = green.toString(16);
        blue = blue.toString(16);

        return `#${red}${green}${blue}`;
      };

      const clusters = [theme];
      for (let i = 0; i <= 9; i++) {
        clusters.push(tintColor(theme, Number((i / 10).toFixed(2))));
      }
      clusters.push(shadeColor(theme, 0.1));
      return clusters;
    }
  }
};
</script>

<style>
.theme-picker .el-color-picker__trigger {
  vertical-align: middle;
}

.theme-picker-dropdown .el-color-dropdown__link-btn {
  display: none;
}
</style>
